Volume 400, Number 1, March II 2003
|Page(s)||L1 - L4|
|Published online||24 February 2003|
Letter to the Editor
Detection of DCO+ in a circumstellar disk
Leiden Observatory, PO Box 9513, 2300 RA Leiden, The Netherlands
2 Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, UK
Corresponding author: E. F. van Dishoeck email@example.com
Accepted: 21 January 2003
We report the first detection of DCO+ in a circumstellar disk. The DCO+ line at 360.169 GHz is observed with the 15 m James Clerk Maxwell Telescope in the disk around the pre-main sequence star TW Hya. Together with measurements of the HCO+ and H13CO+ lines, this allows an accurate determination of the DCO+/HCO+ ratio in this disk. The inferred value of is close to that found in cold pre-stellar cores and is somewhat higher than that measured in the envelope around the low-mass protostar IRAS 16293–2422. It is also close to the DCN/HCN ratio obtained for pristine cometary material in the jet of comet Hale-Bopp. The observed DCO+/HCO+ ratio for TW Hya is consistent with theoretical models of disks which consider gas-phase fractionation processes within a realistic 2-D temperature distribution and which include the effects of freeze-out onto grains.
© ESO, 2003
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